The material in these chapters has been assembled from a large variety of sources. The main source has been the bible of automation "Inside OLE" and the MSDN documentation. A nice thing with Delphi that the source to VCL class libraries is included. Combined with the great debugging capabilities this was a good way to see how things are done in Delphi.
In the second edition of this book the base of COM as we know it is described from the ground up. Besides automation the book covers all interfaces which were needed to realize the integration of the MS Office products, the first target of COM. The book is no longer in press, almost all of the chapters have found their way into the MSDN documentation. But if you can get your hands on a copy, get it.
This book only covers the the Idispatch interface, but does this in such a detail and in such a clear language that it will raise your insight in the internal workings of automation.
In essence just a bundle of printed help files. The book bundles the description of all methods involved in automation interfaces, including their parameters, their type and how to use them. If you want to do some work on the inside, this is a very handy book.
This magazine is entirely dedicated to Delphi. Steve Teixera has done a very valuable series on COM and Brian Long regularly addresses COM problems in the Delphi clinic.